Circuit interrupter



Oct. 3, 1950 D. ELLIS 2,524,287

CIRCUIT INTERRUP'I'ER Filed Jan. 19, 1945 2 Sheets-Sheet l WITNESSES: INVENTOR 4%%%. ,De/bar/AfW/a.

BY 7 I f'TORN Y Oct. 3, 1950 D. ELLIS CIRCUIT INTERRUPTER 2 Sheets-Sheet 2 Filed Jan. 19, 1945 INVENTOR De/berf 705.

WITNESSES:

ATTORNE Patented Oct. 3, 1950 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Pennsylvania Application January 19, 1945, Serial No. 573,569

3 Claims.

This invention relates to circuit interrupters in general, and more particularly to are extinguishing structures therefor.

There is a continuous demand by manufacturers to obtain circuit interrupters or switches of reduced dimensions since considerable quantities of these interrupters or switches are employed in conjunction with machine tool instal lations. Furthermore, mounting space is always at a premium and it is desirable to reduce the external dimensions of such a circuit interrupter or switch as greatly as possible. However, there comes a point in reducing the dimensions of an interrupter or switch at which electrical breakdown occurs across insulating parts separating electrical contacts of the difierent phases, and,-

therefore, it is desirable to confine the arcs drawn in such switches or contactors to certain specified locations at which they will not be permitted to reach insulating parts to render the latter conductive over long periods of operation. Furthermore, it is desirable to confine the arc itself to prevent outward looping thereof, as such looping would ionize the air and might cause fiashover between adjacent phases through the air.

It is, therefore, an object of my invention to provide an improved circuit interrupter having novel arc extinguishing and arc controlling means whereby the arc will not be permitted to contact insulating walls to render the latter conductive during long periods of operation.

It is a more specific object of my invention to reduce the dimensions of circuit interrupters or switches by utilization of my invention so that the dimensions of such interrupters may be con- ;iderably reduced over those which have been used heretofore.

Another object is to provide a. housing composed of conducting material and having at least one portion open, and to provide means for establishing an are adjacent the open portion of the housing. Preferably I form such housing out of a suitable "magnetic material.

Another object is to provide an improved circuit interrupter of the double break type in which each of the arcs drawn will be drawn adjacent the open portion of such a magnetic housing.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the drawings, in which:

Figure l is a fragmentary vertical sectional view through a circuit interrupter embodying my in- 2 vention, the parts being shown in the partially open circuit position;

Fig. 2 is a sectional view taken along the line II-II of Fig. 1;

Fig. 3 is a fragmentary plan view of the lower contact structure showing in plan the magnetic cup utilized;

Fig. 4 is a fragmentary vertical sectional view through the magnetic cup showing somewhat schematically the arc, magnetic field and forces acting on the arc by the distorted magnetic field.

Fig. 5 is a perspective view of the magnetic cup shown in Fig. 1;

Fig. 6 is a. fragmentary vertical sectional view through a double-break circuit interrupter of modified construction; and

Figs. 7 and 8 show modified cup constructions.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numerals I and 2 designate stationary contacts co-operating with the contacting portions 3, 4 of a conducting bridging member 5 resiliently mounted in a support 6, the latter being rigidly secured to an operating member 1 adapted for pivotal movement.

The are 8 drawn between the co-operating contact members i, 3 is moved upwardly into a deionizing structure generally designated by the reference numeral 9 and which is more specifically described in United States Patent 2,356,039, which issued August 15, 1944, to Delbert Ellis and Owen L. Taylor, and which is assigned to the assignee of the instant application.

The arc III which is drawn between the contacts 2, I is established adjacent the open portion of a housing, or semi-enclosure member, generally designated by the reference numeral 1 I and composed of any suitable magnetic material. Preferably the housing has continuous side portions I2 and a bottom portion I3. In a preferred form of my invention as shown in Fig. 1, the magnetic housing is of substantially semispherical configuration as more clearly shown in the perspective view shown in Fig. 5.

The arc H) which is established within the cup II and adjacent the upper end thereof has the magnetic field thereabout distorted as shown in Fig. 4 to consequently draw the arc l0 downwardly until it contacts the bottom l3 of the cup II, at which time the are I0 is broken into two serially related portions designated by the reference numerals ll, IS in Fig. 1.

Following the separation of the are It into two serially related arc portions l4, l5, each portion is moved downwardly by the distorted magnetic field so that a limiting position may be assumed as designated by the dotted lines I6, I! of Fig. l. The exact point at which the arc is drawn depends upon the contact surfaces and in certain instances may be drawn at the sides of the contacts 2, 4 as indicated by the dotted lines in Fig. 3. These dotted lines indicate successive arc positions when the arc is drawn at either one of the two side portions of the contact. Even though this occurs, namely the arc I being drawn at the side edges of the contacts 2, 4, nevertheless the arc 'will, as before, contact the side portions I2 of the cup I I to break into two serially-related portions, each of which will be moved downwardly toward the bottom I3 of the cup II by the distorted magnetic field. As a result of the field set up by the arc and the flux in the steel cup, the arc, whether drawn at' the center of the contacts or at the side portions thereof, continues to move from the single arc loop into the two short arcs until current zero at which time deionization occurs and the voltage is not suflicient to cause restriking and the arc extinguishes.

From the foregoing description, it will be apparent that with the construction shown, the arc I0 is moved away from the portions of the contacts 2, 4 which normally during the closed position have to carry the full load current passing through the interrupter. Thus, the arc is drawn toward the lower extremities of the contacts 2, 4 and eventually may pass to the limiting positions I6, ll, as shown inFig. 1. Consequently, the portions of the contacts 2, 4 which carry the full load current in the closed position are not subjected to pitting or other contact deterioration inasmuch as the are In is quickly moved away from these portions during the interruption thereof.

It will be observed that by utilizing such a housing construction, the are never gets out of the housing and consequently cannot contact insulating material to render the latter conductive. This is particularly desirable for a three-pole switch or interrupter controlling the three phases of a line in which it is necessary to reduce the dimensions of the switch or interrupter to a considerable extent. Thus, inasmuch as the arc ID never gets out of the housing II, the insulation clearance between adjacent phases may be very slight, inasmuch as there is no possibility of insulation breakdown.

The housing II may assume the form of a cup composed of magnetic material as shown in Fig. l secured by a rivet I8 to the base portion I9, or, in certain instances, it may be-desirable to form the housing I I of magnetic mesh material such as shown in Fig. 8 or of perforated magnetic material as shown in Fig. 7. In other words, the cup II does not need to be of continuous solid construction but may be perforated or meshed, the essential feature merely being that suilicient magnetic material is present to cause lateral motion of the are into the cup.

In certain applications it may be desirable to form the housing I I of conducting and not magnetic material. Preferably, however, I employ magnetic material to intensify the attraction of the arc.

Fig. 6 shows a modified form of circuit interrupter of the double-break type in which two cups II are associated with the pair of breaks formed. Consequently in Fig. 6 extinction occurs in a manner previously described at each break:

From the foregoing it will be apparent that I.

have provided a more eilicient arc controlling and extinguishing means than has been provided heretofore. Also, I have prevented the are from burning or forming conducting particles on the surfaces of organic or inorganic insulating materials, which might lead to tracking and dielectric breakdown. The invention consists of a drawn shape cup into which is projected separable contacts, such that when the arc is drawn, it is directed generally into the cup as a result of the magnetic field produced by the current or are path and the steel cup. The shape of the cup and contact relation are such that the magnetic field is always inward toward the bottom of the cup, thus confining the arc to the inside of the cup until extinction occurs.

From the view of the current path shown in Fig. 1 bydotted lines as the contacts separate, a single arc I0 is drawn and is magnetically pulled downward or sideways and downward as illustrated by Figs. 3 and 4 striking the metal cup surface. At this point the arc is divided into two short arcs, reducing the voltage drop across each arc, and, as a result of the field, continues to move along the surface of the cup until current zero, at which time deionizing occurs and the voltage is not sufllcient to cause restriking and extinction takes place.

In Fig. 1, this action occurs simultaneously and in series with the are at the top contact structure which is drawn into the grid structure 9.

The shape of the cup and the field set up by the current retains the arc inside the metal cup to where the arc does not come in contact with the surface of the arc box wall or the base, thus maintaining high dielectric of the insulating material.

In fact, an interrupter made basically of phenolic material embodying my invention which was rated at 50 amperes, 600 volts suitable for use with a 25 horsepower, 600-volt motor was tested at over 300% overload on an horsepower, 600- volt locked rotor motor and after 125,000 operations at this exceedingly high overload, showed no appreciable wear on either the contacts or the magnetic cups, and the dielectric properties of the phenolic materials were not adversely affected.

From the foregoing description, it will be apparent that I have considerably increased the interrupting ability of circuit intei'rupters as a result of utilizing my invention. The scope of my invention is broad and merely by illustrating certain forms it is not to be taken that my invention may not be embodied in other forms.

Although I have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A circuit interrupter including a metallic cup member having at least two substantially parallel side portions, an interconnecting base portion and two end portions, a pair of separable contacts both spaced from the cup member, yet disposed therewithin, for establishing an arc between the side portions and substantially parallel thereto, the end portions of the cup member being disposed immediately adjacent to the back sides of the contacts when the latter are in their open circuit position to prevent thereby lengthening of the are out of the cup member and away therefrom, the end portions also cooperating with the side and base portions to intensify the cooling and deionization of the arc, the facing metallic side portions and the facing metallic base portion being exposed to the arc and in such close proximity thereto that the established arc will actually transfer to the metallic cup member to become subdivided thereby to result in the formation of at least two serially related arc portions.

2. A circuit interrupter including a magnetic cup member having at least two substantially parallel side portions, an interconnecting base portion and two end portions, a pair of separable contacts both spaced from the cup member, yet disposed therewithin, for establishing an are between the side portions and substantially parallel thereto, the end portions of the magnetic cup member being disposed immediately adjacent to the back sides of the contacts when the latter are in their open circuit position to prevent thereby lengthening of the are out of the cup member and away therefrom, the end portions also cooperating with the side and base portions to intensify the cooling and deionization of the arc, the facing magnetic side portions and the facing magnetic base portion being exposed to the arc and in such close proximity thereto that the arc will actually transfer to the magnetic cup member to become subdivided thereby to result in the formation of at least two serially related arc portions, the magnetic field surrounding each of the arc portions being attracted to and entering the base and end portions to cause thereby the arc portions to remain within the magnetic cup member to become extinguished therein.

3. A circuit interrupter including a magnetic semi-enclosure member having at least two substantially parallel side portions, an interconnecting base portion and at least one end portion, a pair of separable contacts both spaced from the semi-enclosure member, yet disposed therewithin,

for establishing an are between the side portions and substantially parallel thereto, said end portion of the semi-enclosure member being disposed immediately adjacent to the back side of one of the contacts when the latter are in their open circuit position to prevent thereby lengthening of the are out of the semi-enclosure member and away therefrom, said end portion also cooperating with the side and base portions to intensify the cooling and deionization of the arc, the facing magnetic side portions and the facing magnetic base portion being exposed to the arc and in such close proximity thereto that the arc will actually transfer to the semi-enclosure member to become subdivided thereby to result in the formation of at least two serially related arc portions, the magnetic field surrounding each of the arc portions being attracted to the semi-enclosure member to thereby cause cooling and extinction of the arc portions.

DELBERT ELLIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,343,793 Schneider June 15, 1920 1,705,700 Austin Mar. 19, 1929 1,798,319 Ellison et al. Mar. 31, 1931 1,827,516 Greenwood Oct. 13, 1931 1,884,572 Chapman Oct. 25, 1932 2,355,959 Dodd Aug. 15, 1944 2,356,039 Ellis et al. Aug. 15, 1944 FOREIGN PATENTS Number Country Date 754,678 France Nov. 10, 1929 

